Are you familiar with the work of the physician and author Oliver Sacks? You might be interested in his book “Musicophilia: Tales of Music and the Brain” if you have not read it.
I am not myself a certified music therapist, but I know they do work with children with autism among other things. Is your background in music therapy, and are you using this with the elderly? That is very interesting.
One anecdote I would like to share: there is a senior’s class I occasionally sub, which I also occasionally take when the regular teacher is in (I think it is good to see things from the participants point of view). She was playing a tape with the song “Blueberry Hill” and as I was in the back I could hear several of the ladies singing happily along as they exercised. I would have to say when I sub I bring old tapes (yes, I was teaching back in the cassette days) with broadway, and even classical music, and I get lots of thanks for the music.